This article has some good insight into why Nintendo did their Nintendo Direct when they did.

The article said the PS3 and 360 could not pull off the visuals from Monolith Soft's X. Is this a fact? I mean, it looks good to me. The only game in the same genre that looks nearly that good is FF XIII, but that has some bad pop-in. I know it's a very, very early build but it looks like X needs some polish. Specifically the grass which also has some bad pop-in and is obviously sprite based. But, as far as I can tell, it's lifted directly from the Wii's Xenoblade Chronicles which makes me think it was just a placeholder for the teaser. The shadows also don't seem complete since they are unaffected by the sun. I imagine that will be fixed too. I'm looking forward to E3 when they hopefully show more footage. Either way, X looks like it'll be a great game, considering its pedigree.

It's hard to say if it's a definite fact because it's subjective and different games prioritize different graphical effects. However I'd say X definitely has more consistently high detailed textures than any equivalents on PS3/360. That's an obvious advantage of the Wii U as it has twice at least twice as much RAM usable for games.

EDIT: I think the grass will remain sprite-based but pop-in should definitely be remedied. Sprite-based grass is the standard and it can achieve approximately the same effect whilst being much less resource intensive.